Simulation And Research Of Nanofiber Multi-Needle Electrospinning Process

Electrospinning technology is a method to realize the continuous preparation of nanofibers by using electric field force.Because of its simple principle and device,it is widely used in the research and development of new nanomaterials in various fields.Among them,multi-needle electrospinning technology has low efficiency compared with traditional single-needle electrospinning and needle-free electrospinning has larger fiber diameter and different quality,showing great advantages in spinning efficiency and spinning quality.The multi-needle nozzle is the core component of the multi-needle electrospinning device,and the arrangement of its needles can directly affect the distribution of the working electric field during the spinning process,which in turn has a significant impact on the quality of the spun fibers.Therefore,in this paper,a multi-needle nozzle with regular hexagonal distribution is proposed,and a series of simulation analysis and experimental research on its electric field distribution and optimization measures are carried out,and the formation process of Taylor cone and jet in the process of electrospinning is theoretically studied.Analysis,numerical simulation and experimental verification,the main contents and conclusions are as follows:(1)Combined with the regular polygon theory and the principle of maximum jet density,a regular hexagonal distributed multi-needle nozzle is designed.The electric field distribution characteristics of the regular hexagonal multi-needle nozzle are analyzed and summarized:the field strength of the needle tip of the same position is similar,and the field strength of the needle tip of the high position is stronger than that of the needle tip of the low position;the high position has a shielding effect on the internal electric field;as the number of needles increases,the electric field distribution is uniform reduce.(2)Based on the electric field distribution characteristics of the regular hexagonal multi-needle nozzle,three measures to optimize the electric field distribution are proposed,and the uniformity of the electric field distribution is characterized by the standard deviation coefficient.Through simulation analysis,the results show that: with the increase of needle spacing,the interaction between needles is weakened,the overall field strength is increased,and the uniformity of electric field distribution is improved,but the jet density is reduced,which is not conducive to improving production efficiency;Needle,the overall average field strength is effectively improved,the standard deviation coefficient is significantly reduced,and the uniformity of the electric field distribution is improved;the shielding ring will weaken the electric field strength at the needle tip to a certain extent,but the effect on the high-position needle is more obvious,so that the field strength distribution can be obtained.Balance and reduce the range of electric field distribution,which is beneficial to obtain the working electric field with concentrated distribution.(3)Numerical simulation of Taylor cone and cone jet shape in the process of electrospinning is carried out.The simulation results show that when the inlet pressure and other parameters are determined and unchanged,too large or too small voltage is not conducive to the formation of Taylor cone.and spinning jets.When the voltage is8 kVthe,Taylor cone cannot be formed;when the voltage is 22 kVthe,jet instability and splitting phenomenon appear.(4)A regular hexagonal 7-needle nozzle was fabricated and a multi-needle electrospinning experimental platform was built.A series of experimental studies were carried out on the above electric field distribution simulation and the numerical simulation of the cone jet shape.The experimental results show that compared with the original 7-pin nozzle,the fiber diameter distribution range of the unequal length7-pin nozzle(25.12-25)is more concentrated,and the average value is small;the fiber diameter distribution range of the 7-pin nozzle with a shielding ring of 8 cm in diameter It was also more concentrated,and the diameter of the fiber collection area changed from 15 cm to 12 cm.The correctness of the simulation conclusion for optimizing the electric field distribution by the unequal needle length method and the shielding ring method is verified.Through the observation of the electrospinning jet morphology under different voltages,it is found that no Taylor cone and stable cone jet are formed at the needle tip when the voltage is less than 7 kV or greater than 21 kV.Although there are differences in the specific values of the voltage range,the The laws and trends shown are consistent with the theoretical analysis and numerical simulation conclusions...